At present, broadband access technologies are mainly categorized into a copper access technology and an optical access technology. An access network implemented by the optical access technology is called an optical access network (OAN). The PON is a point to multi-point transport technology for implementing the OAN. A basic structure of the PON is shown in FIG. 1. The PON includes an optical line terminal (OLT), an optical distribution network (ODN), and optical network units (ONUs). In FIG. 1, the ONU is represented by an optical network terminal (ONT).
The OLT provides a service network interface (SNI) for the OAN and is connected to one or more ODNs. The ODN, a passive optical splitter, transmits downlink data of the OLT to each ONU through optical division, and transmits uplink data of the ONUs to the OLT through convergence. An ONU provides a user-network interface (UNI) for the OAN and is connected to the ODN. The ONU may be called an ONT if the ONU also provides a service interface, such as an Ethernet user port or a plain old telephone service (POTS) port. In the description, both an ONU and an ONT are referred to as an ONT for convenience.
In the PON, the downlink traffic of the OLT is broadcasted to the ONTs by means of time-division multiplexing (TDM), and each of the ONTs receives the downlink traffic as required. Moreover, the OLT manages the uplink traffic of the ONTs, and a specific ONT is allowed to transmit data to the OLT at a particular time by means of time division multiple access (TDMA).
FIG. 2 is a schematic structural view of an ONT supporting Ethernet services in the prior art. Referring to FIG. 2, the ONT includes an Ethernet module, at least one service module based on Ethernet, and a PON protocol processing module.
The PON protocol processing module is adapted to perform PON standard protocol related operations, for example, receiving the OLT configuration information to configure the ONT, reporting the status of the ONT or making an alarm, adding a PON protocol frame header to an uplink packet received by the Ethernet module, or removing a PON protocol frame header from a downlink frame, and then reassembling and sending the frame to the Ethernet module.
The Ethernet module is adapted to perform operations related to the Ethernet frame processing, maintenance, and management, such as adding a virtual local area network (VLAN) tag, or filtering packets based on VLAN tags or media access control (MAC) addresses.
The service module based on Ethernet is adapted to perform functions related to its own service processing, maintenance, and management, such as the recovery of a TDM service module clock based on Ethernet.
The service module based on Ethernet provides a UNI, and is connected to the Ethernet module through an internal UNI provided by the Ethernet module.
In the ONT, a certain port of the Ethernet module only provides Ethernet services instead of services over Ethernet, and thus the internal UNI functions as the UNI of the ONT.
The ONT based on Ethernet services supports various service functions over Ethernet, for example, TDM services based on Ethernet or Internet protocol (IP) routing services.
International Telecommunication Union (ITU-T) defines Broadband Passive Optical Network (BPON) technology G.983.x serial standards and Giga-bit Passive Optical Network (GPON) technology G.984.x serial standards. In the BPON or GPON technology, the configuration and management modes of ONTs by an OLT are defined. In particular, the OLT manages and configures each ONT through an ONT management control interface (OMCI). The OMCI is a configuration transmission channel built between the OLT and each ONT in the BPON or GPON, and established when the ONT is registered to the OLT. Further, the OMCI adopts a master-slave management protocol, in which the OLT is a master device, the ONTs are slave devices, and the OLT controls multiple ONTs connected thereto through the OMCI channels.
The OMCI abstracts various data of the management and configuration of the ONTs by the OLT into an independent management information base (MIB) with management entities (MEs) as its basic units. In the BPON or GPON, the OLT is defined to control various MEs of each ONT through the OMCI. Under the control of the OLT, the ONT implements the configuration and management of each ME. The OMCI is meant to permit the provision of modularization and expandability to satisfy the control and management of different ONTs.
FIG. 3 is a schematic view of an Ethernet service configuration device employing MEs in the prior art. Referring to the figure, a MAC bridge port configuration data ME is set in an Ethernet module of an ONT. An Ethernet flow termination point ME and a pseudo wire termination point ME connected with each other are set in a service module based on Ethernet. The pseudo wire termination point ME is further connected to the MAC bridge port configuration data ME.
The MAC bridge port configuration data ME is adapted to configure data related to a MAC bridge port, for example, parameters about the port priority, port path value, and termination point pointer. The pseudo wire termination point ME defines to transmit TDM service configuration data in the form of data packets. The configuration data includes structured/unstructured service-type attributes and signaling bearer modes. The Ethernet flow termination point ME is adapted to configure parameters required for ending/initiating an Ethernet data frame, such as MAC addresses of the ONTs, remote MAC addresses, and strategies of adding VLAN tags to an uplink frame.
Referring to FIG. 3, the MAC bridge port configuration data ME in the Ethernet module is directly connected to the pseudo wire termination point ME in the service module based on Ethernet. The MAC bridge port configuration data ME may only configure data related to the MAC bridge port, such as parameters about the port priority, port path value, and termination point pointer, instead of configuring a loop-back detection function. That is, the MAC bridge port configuration data ME is unable to detect channel faults of an internal UNI through loop-backs, and thus the loop-back detection function has to be configured by an termination point ME of a certain type of service. In FIG. 3, the loop-back detection function is not defined in the MAC bridge port configuration data ME. When an Ethernet physical interface is directly provided by the Ethernet service module, an physical path termination point Ethernet UNI ME correlated with the MAC bridge port configuration data ME provides a loop-back detection function. However, the device in FIG. 3 does not have the above function, and is thus incapable of performing the loop-back fault detection.
Referring to FIG. 3, the Ethernet flow termination point ME defines some attributes configured to process the Ethernet data. However, the Ethernet flow termination point ME is directly correlated with the pseudo wire termination point ME instead of the MAC bridge port data ME, i.e., the ME that should be employed to configure the Ethernet data attributes is set in the service module based on Ethernet, and is uncorrelated with the Ethernet module. Thus, the device in FIG. 3 deviates from the design principle of modularization. As a result, a close coupling between the Ethernet service configuration and all kinds of service and/or device configurations based on Ethernet is generated, and the ONT maintenance and modularization configuration will be affected.